The invention relates to a shaving razor that conforms to the surface being shaved.
Shaving razors typically have straight cutting edges, while the surfaces being shaved having varying degrees of flatness or curvature and varying abilities to deform to provide a flat surface for the straight edge of the razor. Shaving an area of the body with pronounced curvature, e.g., an ankle or knee, using a razor having a straight cutting edge results in a localized area of contact. This requires repeated strokes to shave the entire area, and causes a high stress concentration at the localized area of contact, which can increase the possibility of a nick or cut at that area.
In one aspect, the invention features, in general, a shaving razor including a handle, three blade units that are mounted at the end of the handle, and a mounting structure connecting each blade unit to the handle. Each blade unit includes a guard, at least one blade having a cutting edge, and a cap. The mounting structure provides a pivotal connection of the blade unit to the mounting structure about a pivot axis that is transverse to the cutting edge, and also provides up and down movement of the blade unit along a displacement direction that is transverse to a plane through the guard and cap, thereby permitting each blade unit to conform to the contour of a surface being shaved.
In another aspect, the invention features, in general a shaving razor including a handle and a blade unit that is mounted at the end of the handle by a parallelogram, four-bar linkage made of an integral plastic piece including two elongated members, a proximal end member connected to the handle, and a distal end member connected to the blade unit. The elongated members and proximal and distal end members are pivotally connected to each other via resilient living hinges permitting up and down movement of the blade unit.
In another aspect the invention features, in general, a shaving razor including a handle and three blade units that are mounted at the end of the handle by a mounting structure. The cutting edges of blades of two of the blade units are generally aligned with each other and have a gap between them, and the third blade unit Is offset with respect to the other two, with its blade overlapping the gap. The aligned blade units have facing cutout portions in respective caps, and the third blade unit is partially located in the region of the cutout portions.
Embodiments of the invention may include one or more of the following features. The mounting structure for each blade unit is independent of mounting structures for the other blade units, permitting each blade unit to pivot about a respective pivot axis and to be displaced along a respective displacement axis independently of the pivoting and displacement of the other blade units. The integral plastic piece of the four-bar linkage has an at rest position in which the elongated members are spaced from each other and a stop position in which the elongated members contact each other, and the piece is resiliently deformed at the living hinges to provide a force resisting movement from an at rest position to a stop position, the blade unit moving up and down along the displacement axis as the elongated members move toward and away from each other. The mounting structure has a second living hinge providing pivoting about the pivot axis, the second living hinge being resiliently deformed to provide a force resisting pivoting about the pivot axis from a neutral position. Planes through the guards and caps of the blade units are generally coplanar when in an at rest position with respect to the displacement axis and at a neutral position with respect to the pivot axis. The cutting edges of blades of the first and second units are generally aligned with each other and have a gap between them, and a third blade unit is offset with respect to the first and second blade units, with its blade overlapping the gap during all positions of pivoting and up and down movement. The blades of the blade units are between xc2xcxe2x80x3 and xc2xexe2x80x3 long (preferably between xe2x85x9cxe2x80x3 and ⅝xe2x80x3 long, and most preferably about xc2xdxe2x80x3 long). The blade units are mounted to resist displacement from an at rest position with a spring constant of between 5 and 30 (preferably between 10 and 29, and most preferably about 15) gm force/mm . The blade units are mounted to resist pivoting about the pivot axis from the neutral position with a spring constant of between 3 and 20 gram-millimeters/radian. The plastic of the mounting structure is an elastomeric polymer, preferably a polyethylene block amide available under the PEBAX trade designation. The integral plastic piece is between 0.008 to 0.018 inch thick (preferably 0.012 to 0.014 inch) at the living hinges providing the up and down movement. The integral plastic piece is between 0.006 to 0.014 inch thick (preferably 0.009 to 0.011 inch) at the living hinge providing pivoting. The mounting structure can also provide pivoting about an angle parallel to the cutting edge. The mounting structure can be mounted at an angle with respect to the handle. Each blade unit has plural blades.
In other aspects, the invention features, in general, a shaving razor handle having a shape that is comfortable and permits a variety of different grips to be used. In one aspect, the upper surface of the handle has an elongated index finger indent that is sufficiently long to support multiple segments of an index finger. In another aspect the lower surface of the handle has an elongated thumb indent that is sufficiently long along a longitudinal axis to support both segments of a thumb oriented along the longitudinal axis. In another aspect, the upper surface of the handle is sufficiently long and the distal region is curved and shaped so as to fit in the palm of a user when an index finger is placed at a proximal region of the upper surface. In another aspect, side surfaces of the handle have a neck region between two wider regions, the neck region being sufficiently long to receive a thumb on one side and a plurality of fingers on the other side. The index finger indent is about ⅝xe2x80x3 wide and about 2xc2xcxe2x80x3 long, and the thumb indent is about 1xe2x80x3 wide and about 3xe2x80x3 long. The thumb indent has a lip at its distal end to indicate the end of the indent to the user. The thumb indent is scooped in an axis that is transverse to the longitudinal axis with a sufficient curvature to receive the end segment of a thumb oriented along the transverse axis.
Embodiments of the invention may include one or more of the following advantages. The razor provides a conforming blade system in which the force is evenly distributed over areas of pronounced curvature. There is more blade contact on curved surfaces with the result that shaving is faster and more efficient. There are lower stresses developed with the result that the razor glides smoothly across the surface. The razor is self-adjusting, making it easy to use. The razor conforms to pronounced curvature with application of low forces on the blade units and adjusts to both convex and concave surfaces. The shaving razor maintains local shaving geometry on the skin (e.g., blade angle and exposure), at the same time that it provides more contact and adjusts to the curvature. The composite overall size of the series of blade units is similar in length to an ordinary cartridge. There are no unshaven stripes between the individual blade units. The footprint of the blade units fits into tight areas. The flexure arms deflect in a controlled manner. The individual blade units do not interfere with each other. The razor achieves even load distribution among the individual blade units, providing maximum percentage contact area for each blade unit. The razor has uniform load distribution across each blade unit. The stiffness of the arms is selected to maintain contact with the skin to thereby avoid vibration. The four-bar linkage provides up and down motion while maintaining the orientation of the plane of the blades"" cutting edges. The shaving razor provides a smooth, safe and comfortable shave. The handle conforms to fit naturally in the user""s hand and accommodates many grip styles. It has soft gripping materials in key locations.
Other advantages and features of the invention will be apparent from the following description of preferred embodiment thereof and from the claims.